It sounds like you may have accidentally deleted or modified the code for the slide show and featured collections on your home page. Here are a few steps you can try to get it back:
Check the theme’s documentation: The theme’s developer may have documentation on how to set up the slide show and featured collections on the home page. This can be a good starting point for getting the functionality back.
Check the theme’s demo: The theme’s demo may have the slide show and featured collections set up the way you want, you can use the demo as a reference to set it up on your site
Check the theme’s settings: Look for a settings or customization options in the Shopify admin, it could be that you accidentally turned off the slide show or featured collections.
Check the theme’s code: Look for the code that controls the slide show and featured collections in your theme’s code. You may be able to find the code in the theme’s “sections” or “templates” folder. If you find the code and it’s not present in the theme’s homepage, you can add it back in
If all else fails, you can try reaching out to the theme’s developer for support. They may be able to help you restore the slide show and featured collections on your home page.